Corrosion testing instrument



FIG. 1 is a left front perspective view of a corrosion testing instrument showing my new design; the right side being identical;

FIG. 2 is a front elevational view thereof, the rear being flat, plain and unornamented; and

FIG. 3 is a cross-sectional view thereof as taken from line III--III of FIG. 2.

The top and bottom of the instrument are flat, plain, and unornamented. 

The ornamental design for a corrosion testing instrument, as shown and described. 